Multi-robot systems have been widely applied to various applications to perform a given task collaboratively and cooperatively. In a multi-robot environment, path-planning or collision avoidance is an important problem. This paper tackles this important but challenging problem. We developed a step-forward approach for collision avoidance in multi-robot systems, building on the established techniques from omni-directional vision systems, automatic control, and dynamic programming. The developed collision avoidance algorithms can help avoid the collision from any static obstacles and any dynamic objects such as a moving robot. In this paper, we report the developed collision avoidance algorithms, along with simulation-based experimental results. The results show that the collision avoidance strategies are effective and useful for making decisions on collision avoidance in multi-robot systems.